CN115280562A

CN115280562A - Fuel cell

Info

Publication number: CN115280562A
Application number: CN202180020860.XA
Authority: CN
Inventors: 菊池勇
Original assignee: Toshiba Corp; Toshiba Energy Systems and Solutions Corp
Current assignee: Toshiba Corp; Toshiba Energy Systems and Solutions Corp
Priority date: 2020-06-23
Filing date: 2021-05-27
Publication date: 2022-11-01
Also published as: JP7342268B2; JPWO2021261166A1; US20230006238A1; WO2021261166A1; CA3170929A1

Abstract

The invention provides a fuel cell, which can ensure the gas sealing performance of a sealing member without depending on the mechanical strength of a gas manifold, and realize the prevention of the reduction of the gas sealing performance and the reduction of the cost. The fuel cell includes: a fuel cell stack; a pair of end plates that fasten and hold the fuel cell stack from both ends; and a plurality of gas manifolds fixed to the fuel cell stack and the end plates via seals for supplying a fuel and an oxidant to the fuel gas flow passages and the oxidant gas flow passages of the fuel cell stack, respectively, wherein the fuel cell includes a gas manifold fixing band including: a pressure plate disposed in contact with a back surface of the gas manifold; a platen coupling portion that couples platens provided on the back surfaces of adjacent gas manifolds to each other; and a belt fastening part for connecting and fastening the series of pressing plates and the two ends of the pressing plate connecting part.

Description

Fuel cell

Technical Field

Embodiments of the present invention relate to a fuel cell.

Background

A fuel cell is a power generation device configured by stacking a plurality of unit cells, and supplying a fuel such as hydrogen and an oxidant such as air to a fuel cell stack to perform an electrochemical reaction, thereby directly converting chemical energy of the fuel into electric energy and taking out the electric energy to the outside. Each unit cell of the fuel cell stack includes an anode electrode and a cathode electrode disposed on both sides of an electrolyte, and a separator between the electrodes.

The separator is provided with a fuel gas flow path and an oxidant gas flow path that are in contact with the anode electrode and the cathode electrode. A pair of end plates are provided at both ends of the fuel cell stack, and the fuel cell stack is held by fastening the fuel cell stack from the stacking direction of the unit cells by the end plates.

Further, in the fuel cell, a gas manifold is provided for supplying the fuel and the oxidizing agent to the fuel gas flow passage and the oxidizing agent gas flow passage of the separator. The method of mounting the gas manifold outside the fuel cell stack is called an external manifold method. In the external manifold type fuel cell, the gas manifold is fixed to the end plate.

When the gas manifold is fixed to the end plate, elastic seals are interposed between the fuel cell stack and the gas manifold and between the end plate and the gas manifold. In the fuel cell, the provision of such a seal prevents the gas inside the fuel cell stack and the gas manifold from leaking to the outside of the fuel cell stack and the gas manifold.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5086581

Disclosure of Invention

Technical problem to be solved by the invention

In the fuel cell, gas or cooling water may flow in the fuel cell during operation of the fuel cell, and the vicinity of the center of the gas manifold may expand, thereby deforming the gas manifold in a direction away from the fuel cell stack. In this case, the gas manifold is deformed, and the seal may peel off from any of the fuel cell stack, the end plate, and the gas manifold, thereby reducing the gas tightness of the seal.

In recent years, the capacity of fuel cells has been increased, and along with this, the fuel cells tend to be larger. Therefore, the amount of deformation of the gas manifold also increases, and the seal is easily peeled off from the gas manifold or the like. As a result, it is difficult to ensure gas tightness of the seal.

In order to prevent the deterioration of the gas tightness of the seal, it is necessary to suppress the deformation of the gas manifold, and it is important that the gas manifold has sufficient mechanical strength. Therefore, consider

(1) The gas manifold is made of a material which is not easily elastically deformed,

(2) The gas manifold is a thick plate structure,

(3) A structure in which a rib is provided on the back surface of the gas manifold, and the like are adopted.

However, if a sufficient mechanical strength is provided to the gas manifold, the gas manifold itself becomes expensive in the above (1) and (2), and the manufacturing cost increases in the above (3), which causes a problem of a rise in the cost. Therefore, in the conventional fuel cell, it is desired to reduce the cost while preventing the reduction of the gas sealing property by the seal member. In particular, in recent years when the capacity of fuel cells has increased, the cost has also increased, and therefore cost reduction has become a priority.

The invention aims to provide a fuel cell, which can ensure the gas tightness of a sealing member without depending on the mechanical strength of a gas manifold, and realize the prevention of the gas tightness and the reduction of the cost.

Means for solving the problems

The fuel cell of the embodiment includes: a fuel cell stack including a plurality of unit cells stacked together, each of the unit cells including an anode electrode and a cathode electrode disposed on both sides of an electrolyte, and a separator disposed in contact with each of the anode electrode and the cathode electrode and having a fuel gas flow passage and an oxidant gas flow passage; a pair of end plates that fasten and hold the fuel cell stack from both ends; and a plurality of gas manifolds fixed to the fuel cell stack and the end plates via seals for supplying a fuel and an oxidant to the fuel gas flow passages and the oxidant gas flow passages of the fuel cell stack, respectively, wherein the fuel cell includes a gas manifold fixing band including: a platen provided in contact with a back surface of the gas manifold; a platen coupling portion that couples the platens provided on the back surfaces of the adjacent gas manifolds to each other; and a band fastening part for connecting and fastening the series of pressing plates and the two ends of the pressing plate connecting part.

Drawings

Fig. 1 is a perspective view of the first embodiment.

Fig. 2A is a side view of the first embodiment.

Fig. 2B isbase:Sub>A sectional viewbase:Sub>A-base:Sub>A of the first embodiment.

Fig. 3 is an exploded perspective view of the first embodiment.

Fig. 4 is an enlarged exploded perspective view of a main portion of the first embodiment.

Fig. 5A is a side view of the first embodiment of the gas manifold fixing band in a state before fastening.

Fig. 5B is a B-B sectional view of the state before fastening of the gas manifold fastening band of the first embodiment.

Fig. 6 is a perspective view of the second embodiment.

Fig. 7A is a side view of the second embodiment.

Fig. 7B is a cross-sectional view C-C of the second embodiment.

Fig. 8 is a perspective view of the third embodiment.

Fig. 9A is a side view of the third embodiment.

Fig. 9B is a cross-sectional view E-E of the third embodiment.

Fig. 10 is a perspective view of the fourth embodiment.

Fig. 11 is a perspective view of a fuel cell provided with a steel belt.

Fig. 12A is a side view of a fuel cell provided with a steel belt.

Fig. 12B is a cross-sectional F-F view of a fuel cell provided with a steel strip.

Fig. 13 is a partial cross-sectional view of a fuel cell stack.

Detailed Description

Hereinafter, the fuel cell of the embodiment will be described with reference to the drawings.

(first embodiment)

Fig. 1 isbase:Sub>A perspective view showing the structure ofbase:Sub>A fuel cell ofbase:Sub>A first embodiment, fig. 2A isbase:Sub>A side view, fig. 2B isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A of fig. 2A, and fig. 3 is an exploded perspective view. As shown in these figures, the fuel cell stack 1 is fixed in a stacked state by fastening a pair of end plates 2 with a plurality of tie rods 3. Fig. 13 is a partial sectional view of the fuel cell stack 1. As shown in fig. 13, the fuel cell stack 1 is configured by stacking a plurality of unit cells 11, each of the unit cells 11 includes an anode 111 and a cathode 112 disposed on both sides of an electrolyte 110, and a separator 12, and the separator 12 is disposed in contact with each of the anode 111 and the cathode 112 and has a fuel gas flow path F121 and an oxidizing gas flow path F122. For example, the fuel gas flow path F121 and the oxidizing gas flow path F122 extend in directions orthogonal to each other, the fuel gas flow path F121 extends in a direction orthogonal to the paper surface in fig. 13, and the oxidizing gas flow path F122 extends in a direction along the paper surface in fig. 13.

A resin gas manifold 5 is attached to each side surface of the fuel cell stack 1 and the end plate 2 via a seal 4. The gas manifold 5 is fixed to the end plates 2 and the fuel cell stack 1 by screwing gas manifold fixing bolts 6, which pass through holes at both ends of the gas manifold 5, into threaded holes of the end plates 2. The gas manifold 5 is used to supply the fuel and the oxidant to the fuel gas flow channels and the oxidant gas flow channels of the fuel cell stack 1, respectively.

A gas manifold fixing band 7 is provided around the center of the gas manifold 5 so as to be wound around the outside of the gas manifold 5 on the 4-face side. As shown in fig. 4, the gas manifold fixing band 7 includes a pressure plate 7a, a pressure plate coupling portion 7b, and a band fastening portion 7c.

The pressure plate 7a is a steel plate-shaped member, has mechanical strength (rigidity) to such an extent that it is not largely deformed even in a state where the gas manifold fixing band 7 is fastened, and has a smooth contact surface with the gas manifold 5 and a small frictional resistance with the gas manifold 5. The platen 7a is formed of a member thicker and more rigid than the platen coupling portion 7 b.

The platen coupling portion 7b is a thin plate-like member of a steel material that has been bent in advance, is provided so as to be in contact with the platen 7a, and is provided in a state in which the platen 7a is pressed in the direction of the gas manifold 5 when the gas manifold fixing band 7 is fastened. The platen coupling portion 7b has a rigidity of a degree that it can deform when fastened by the band fastening portion 7c, and is formed of a member thinner and lower in rigidity than the platen 7 a. Fig. 4 shows a platen and a fixing screw 7d of the coupling portion for fixing the platen 7a and the platen coupling portion 7 b.

A band fastening portion 7c is provided at both ends of the series of the presser plate 7a and the presser plate coupling portion 7 b. The band fastening portion 7c is 2 members connected to both ends of the platen connecting portion 7b, and is configured as follows: by fastening in a direction in which the distance between the bolts 7e and the nuts 7f becomes smaller, the respective pressure plates 7a are pressed against the gas manifold 5. A fastening portion elastic body 7g made of an elastic body such as a disc spring, a coil spring, or rubber is inserted between the bolt of the fastening portion and the band fastening portion 7c.

When the gas manifold fixing band 7 is tightened, the seal 4 is compressed and deformed, the gas manifold 5 moves in the direction of the fuel cell stack 1, and the platen 7a moves relative to the gas manifold 5 according to the amount of movement of the seal, but the platen connecting portion 7b does not contact the gas manifold 5 even if the platen 7a moves. In the present embodiment, the length of the platen 7a is longer than the length of the surface in contact with the gas manifold 5, so that the platen coupling portion 7b is not in contact with the gas manifold 5 even when the platen 7a moves. As shown in fig. 3, the gas manifold 5 is provided with a pipe connection portion 8 for the gas manifold.

(action and Effect)

Fig. 2B is a cross-sectional view showing a state in which the gas manifold fixing band 7 is fastened in the first embodiment. As shown in fig. 2B, the seal 4 between the gas manifold 5 and the fuel cell stack 1 is thinner and crushed than the state before the gas manifold fixing band 7 is fastened as shown in fig. 5B, and the gas manifold 5 is closer to the fuel cell stack 1 in the state of fig. 2B.

At this time, since the platen coupling portion 7b is a thin plate-like member, the bending angle of the bent portion of the platen coupling portion 7b changes at the contact position with the corner portion of the platen 7a, and the platen 7a is kept in contact with the back surface of the gas manifold 5. However, since the length of the platen coupling portion 7b hardly changes, the platen 7a moves with respect to the gas manifold 5.

In fig. 2B, the left and right press plates 7a in the cross-sectional view slide upward at the same time when the state is changed from fig. 5B to fig. 2B. The band fastening portion 7c also slides toward the center. However, even if the pressure plate 7a slides, a force that presses the gas manifold 5 in the direction of the fuel cell stack 1 via the pressure plate coupling portion 7b and the pressure plate 7a is generated due to the fastening force that fastens the gas manifold fastening band 7. Further, since the frictional resistance of the contact surface between the pressure plate 7a and the gas manifold 5 is small, the gas manifold 5 does not move in the horizontal direction with respect to the contact surface with the seal 4, and a uniform compressive load is applied to the seal surface to ensure sealability.

For comparison, fig. 11, 12A, and 12B show a conventional fuel cell provided with the steel strip 11. In this way, when the thin steel strip 11 is directly provided on the outer periphery of the gas manifold and fastened by the steel strip fastening portion 11a, if the seal is crushed by the fastening, the steel strip 11 slides and moves on the gas manifold, the bent portion of the steel strip contacting the corner portion of the gas manifold also moves and is stretched, and a new bent portion is formed at the portion contacting the corner portion of the manifold.

However, if the thickness of the steel strip 11 is not sufficiently thin, the gas manifold is stretched by the bent portion of the steel strip 11 to move in the horizontal direction with respect to the contact surface with the seal member along with the movement of the steel strip 11, or a uniform compressive load is not applied to the seal surface. Further, when the thickness of the steel strip 11 is small, a sufficient tightening force cannot be applied because of low tensile strength, or the steel strip is used in a state where tensile stress is large, so that the sleep strain becomes large, and the tightening force tends to decrease with time.

In contrast, in the first embodiment, the above-described operation and effect can be obtained.

(second embodiment)

Fig. 6, 7A, and 7B show the structure of a fuel cell of the second embodiment. In the first embodiment described above, as shown in the enlarged exploded perspective view of the main part of fig. 4, the platen coupling portion 7b of the gas manifold fixing band 7 is formed of 1 steel thin plate-like member that is integrally connected. In contrast, in the second embodiment, as shown in fig. 6, 7A, and 7B, the platen coupling portion 7B of the gas manifold fixing band 7 is a member that couples 2 adjacent platens 7A, and is formed of a thin plate-like member made of 4 steel materials in total. The other structure is the same as that of the first embodiment. The operation and effect are also the same as those of the first embodiment.

(third embodiment)

Fig. 8, 9A, and 9B show the structure of a fuel cell according to a third embodiment. As shown in fig. 8, 9A, and 9B, in each gas manifold 5 of the third embodiment, a convex portion 5a is provided at a portion that contacts a pressure plate 7a of a gas manifold fixing band 7. A plurality of the projections 5a are provided, and in the examples shown in fig. 8, 9A, and 9B, 3 projections are provided on each gas manifold 5 at intervals. These protrusions 5a protrude the vicinity of the seal portion (the portion where the seal 4 shown in fig. 3 is located) toward the platen 7a, and reduce the contact resistance with the platen 7 a. The other structure is the same as that of the first embodiment.

The operation and effect are the same as those of the first embodiment, but since the contact resistance between the gas manifold 5 and the platen 7a is reduced, the gas manifold 5 is less likely to move in the horizontal direction with respect to the contact surface with the seal 4, or the surface pressure of the seal surface is less likely to become uneven, and the sealing property is more likely to be ensured.

(fourth embodiment)

Fig. 10 shows the structure of a fuel cell of the fourth embodiment. In the first embodiment, both end portions of the gas manifold 5 are fixed to the end plate 2 by the gas manifold fixing bolts 6, but as shown in fig. 10, in the fourth embodiment, the following structure is employed: portions of both ends of the gas manifold 5 are also fixed with gas manifold fixing bands 7. Therefore, a total of 3 gas manifold fixing bands 7 are used. The other structure is the same as that of the first embodiment. The operation and effect are also the same as those of the first embodiment.

(other embodiments)

The embodiments described above are presented as examples of the embodiments of the present invention, and are not intended to limit the scope of the present invention. The embodiments of the present invention may be implemented in other various forms, and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

For example, the friction coefficient may be reduced by applying a lubricant to one or both sides of the contact surface of the gas manifold 5 of the platen 7a, or by attaching a member having low frictional resistance.

For example, the platen coupling portion 7b may be made of a steel material other than a thin plate, as long as the relative angle between the adjacent platens 7a is changed to maintain the state in which the platens 7a are in contact with the back surface of the gas manifold 5, and the hook portions may be engaged with both end portions of the platen 7a by using a member having hook portions at both ends, so that the coupling angle between the platen coupling portion 7b and the platen 7a is variable.

Further, the gas manifold fixing band 7 may be combined with other fixing methods, and if it is 1 or more, it may be used in any place.

[ description of reference numerals ]

1, 8230, 2, 8230, end plate, 3, 8230, sealing element, 5, 8230, gas manifold, 5, 8230, convex part, 6, 8230, fixing bolt, 8230, gas manifold fixing bolt, etc 7 \8230, 7a \8230, 8230, 7b \8230, 7c \8230, 8230, 7d \8230, 8230, fixing screw, fixing screw and fixing screw 7e 8230, (82308230sign), connection part bolts, 7F (8230sign), 8230sign, connection part nuts, 7g (8230sign), 8230sign, connection part elastomer, 8 (8230sign), 8230sign, piping connection part of gas manifold, 11 (8230sign), 8230sign, unit cell, 12 (8230sign, diaphragm, 110 (8230sign), electrolyte, 111 (8230sign, anode electrode, 112 (8230sign), 8230sign, cathode electrode, F121 (8230sign), 8230sign, fuel gas circulation path, F122 (8230sign), oxidant gas circulation path.

Claims

1. A fuel cell includes:

a fuel cell stack including a plurality of unit cells stacked together, each unit cell including an anode electrode and a cathode electrode arranged on both sides of an electrolyte, and a separator having a fuel gas flow path and an oxidant gas flow path, the separator being arranged in contact with each of the anode electrode and the cathode electrode;

a pair of end plates that fasten and hold the fuel cell stack from both ends; and

a plurality of gas manifolds fixed to the fuel cell stack and the end plates with a seal interposed therebetween for supplying a fuel and an oxidant to the fuel gas flow passages and the oxidant gas flow passages of the fuel cell stack,

the fuel cell is characterized by comprising a gas manifold fixing band, and the gas manifold fixing band is provided with:

a platen provided in contact with a back surface of the gas manifold;

a platen coupling portion that couples the platens provided on the back surfaces of the adjacent gas manifolds to each other; and

and a band fastening part for connecting and fastening the series of pressing plates and the two ends of the pressing plate connecting part.

2. The fuel cell according to claim 1,

the platen coupling portion is formed of a thin plate-like member that is deformable when the belt fastening portion is fastened,

the platen is formed of a plate-shaped member thicker than the platen coupling portion and having a high rigidity.

3. The fuel cell according to claim 2,

the platen is longer than a back surface of the gas manifold with which the platen is in contact, and the platen coupling portion is not in contact with the gas manifold.

4. The fuel cell according to any one of claims 1 to 3,

the gas manifold is provided with a frictional resistance reduction means for reducing frictional resistance between the back surface of the gas manifold and the platen.

5. The fuel cell according to claim 4,

the frictional resistance reduction means is a projection provided on the back surface of the gas manifold so as to reduce the contact area between the back surface of the gas manifold and the platen.